Showing papers on "Relaxation oscillator published in 2001"

Dynamics of relay relaxation oscillators

Abstract: Relaxation oscillators can usually be represented as a feedback system with hysteresis. The relay relaxation oscillator consists of relay hysteresis and a linear system in feedback. The objective of this work is to study the existence of periodic orbits and the dynamics of coupled relay oscillators. In particular, we give a complete analysis for the case of unimodal periodic orbits, and illustrate the presence of degenerate and asymmetric orbits. We also discuss how complex orbits can arise from bifurcation of unimodal orbits. Finally, we focus on oscillators with an integrator as the linear component, and study the entrainment under external forcing, and phase locking when such oscillators are coupled in a ring.

Analog simulation of the dynamics of a van der Pol oscillator coupled to a Duffing oscillator

Abstract: This paper studies, with analog simulators, the dynamics of a system consisting of a van der Pol oscillator coupled to a Duffing oscillator. Amplitude-response curves are obtained in the case of internal resonance. The jump or hysteresis phenomenon is found. Various bifurcations are observed, and it is found that chaos can appear suddenly, through period-adding or through torus breakdown. The experimental results are compared with the numerical solutions.

Synchronization of oscillators coupled through narrow-band networks

Abstract: The ability of two coupled oscillators to synchronize depends critically on the coupling network. Previous analyses have accurately predicted the performance of quasi-optical microwave oscillator arrays for both weak and strong coupling, but have been limited to coupling networks with bandwidths considerably larger than the locking bandwidths of the oscillators. In this paper, the authors develop a method for deriving a suitable system of nonlinear differential equations describing the oscillator amplitude and phase dynamics using a generalization of Kurokawa's method. The method is applied to the case of two Van der Pol oscillators coupled through a resonant network for a wide range of coupling strengths and bandwidths. Simple approximate formulas are developed for the size of the frequency locking region as functions of the basic circuit parameters.

Dual mode relaxation oscillator generating a clock signal operating at a frequency substantially same in both first and second power modes

Abstract: A microcontroller having a dual mode relax oscillator that is trimmable. In one embodiment, the present invention provides a relaxation oscillator circuit comprising two current sources for establishing a reference voltage for use in causing the relaxation oscillator circuit to operate in two power modes, and a control coupled to both current sources for switching between power modes. In one embodiment, one power mode is a low power mode for standard operation of the microcontroller and one power mode is a very low power mode for use in a sleep mode. In one embodiment, the relaxation oscillator circuit further comprises digitally trimmable components operable to control a current charging a capacitor of the relaxation oscillator circuit to account for process variation in the capacitor, wherein the current is for controlling a frequency of the microcontroller.

A band-switched integrated voltage controlled oscillator

Abstract: The source to drain capacitance of a FET device is used by connecting the source and drain together electrically so as to form a two terminal capacitive device which may be switched into and out of a parallel resonant circuit. Thus, sets of FET devices with their sources and drains connected together are employed in a circuit which produces an output voltage signal at a frequency which is tunable within a plurality of different individual bands. The resultant voltage controlled oscillator is particularly useful in cellular telephone and related wireless systems and/or in any other situation where integrated high frequency voltage control oscillator circuits are desired.

DC-to-DC converter and electronic device using the same

Abstract: A DC-to-DC converter is provided with an astable multivibrator containing a first time constant circuit for setting an ON period of an output and a second time constant circuit for setting an OFF period of the output, and provided with a switching element controlled by the output. The output voltage is controlled by changing the duty ratio of the astable multivibrator in accordance with the output voltage.

The effect of mismatch and disturbances on the quadrature relation of a cross-coupled relaxation oscillator

Abstract: Cross-coupled relaxation oscillators are capable of producing two stable and highly accurate, quadrature output signals. We present a complete high-level model of the cross-coupled relaxation oscillator in terms of circuit parameters, from which we obtain explicit expressions for duty-cycle, oscillation frequency and output phase relation. They predict the influence of mismatches and other disturbances such as delays, at circuit level. The results provide useful guidelines for the design of a high performance circuit of such an oscillator. The theoretical results are confirmed by simulation and by experiment.

Frequency acquisition for data recovery loops

Abstract: A frequency monitor includes an edge detector which produces a pulse for each rising or falling edge of an error signal. The error signal itself has a frequency that is responsive to a difference between frequencies of two input signals. A switched capacitor circuit has an effective average resistance that depends on the rate or frequency of the edge detector output pulses. A capacitor holds a charge that depends on the effective average resistance of the resistive circuit. Finally, comparator produces an output based on the charge held by the capacitor. The comparator output indicates whether the difference between the two input signal frequencies is less than some predetermined amount. A selector, responsive to the comparator, selects from a data phase detector circuit and a frequency acquisition circuit to control an oscillator. The oscillator produces a clock signal at a sampling frequency, which is used by the detector circuit to receive data.

Semiconductor integrated circuit and optical transfer unit

Abstract: In a semiconductor integrated circuit comprising a PLL circuit including an LC resonance type voltage-controlled oscillator which oscillates at the oscillation frequency depending on the control voltage applied, a phase comparator PHC for comparing the phase of an oscillation output signal φ b of said voltage-controlled oscillator with the phase of the reference clock φ r, and a loop-filter LPF for outputting a voltage depending on the phase difference based on an output of the phase comparator PHC, this semiconductor integrated circuit further comprises a plurality of voltage-controlled oscillators VCO1, VCO2, . . . which include different center frequencies of the frequency variable range and the selecting unit for selecting only one oscillator from a plurality of said voltage-controlled oscillators VCO1, VCO2, . . . Accordingly, the semiconductor integrated circuit comprising the PLL circuit using the LC resonance type voltage-controlled oscillator having excellent phase noise characteristic and assuring the desired frequency variable range can be manufactured with higher manufacturing yield.

A capacitive-sensor interface circuit based on a first-order charge-balanced SC-oscillator

Abstract: A new smart interface for capacitive sensors, which are shunted by a parasitic conductance is presented In the novel interface circuit, the effect of shunting conductance is reduced by using the charge/discharge method in a first-order charge-balanced SC-oscillator. The effect of the stray capacitances is eliminated by using the two-port measurement. Moreover, all multiplicative and additive errors of the interface are also eliminated by using auto-calibration and chopping.

Voltage controlled oscillator, voltage controlled oscillator device and radar device

Abstract: A voltage controlled oscillator, a voltage controlled oscillator device, and a radar device provided therewith which can detect when the oscillation frequency becomes uncontrollable. According to one embodiment, a Gunn or other oscillation device is connected to a main line and a varactor diode which is a variable reactance element is connected between the main line and a sub line to constitute a voltage controlled oscillator. A control voltage is applied to the varactor diode via a switching circuit, and the presence or absence of oscillation or a failure of the varactor diode or oscillation device is detected by a detection signal, for example, from the varactor diode as monitored by a voltage monitor, and/or from the oscillation device, as monitored by a current sensing device.

Apparatus and method for a thermal feedback oscillator

Abstract: A method and apparatus is directed to generating an oscillation frequency utilizing the thermal heat transfer properties of semiconductor material as a feedback loop in an oscillator. The oscillator includes a comparator that compares two input signals and enables one of two heater circuits. Each heater circuit is thermally coupled to a sensor and reference circuit. Each sensor and reference circuit pair is arranged such that the reference circuit is heated while the sensor cools. The combination of each sensor and reference circuit produces input signals for the comparator. The frequency of the oscillator is determined by the heat transfer rate between the heater circuit and the corresponding sensor, and the thermal cooling rate of the other sensor. Changing the biasing currents, and distances between the heat sources and the thermal sensors adjust the duty cycle and frequency.

Oscillator averaging phase shift generator

Abstract: Two oscillators, such as in two pulse width modulator circuits of DC to DC power converters, are maintained in synchronization and at a predetermined phase shift from one another by a circuit incorporating a comparator. A sawtooth signal output from the master oscillator is fed to one comparator input while the sawtooth signal is filtered and applied to the second input of the comparator to generate an approximately 180° phase shift turn-on at the output of the comparator that is fed through a driver circuit to an input of a second oscillator. By insuring that the faster operating oscillator is the master, the slave oscillator will be triggered by the signal from the master.

Phase-locking of an InP/InGaP/InGaAs resonant tunneling diode relaxation oscillator by direct optical injection

Abstract: Optical-injection locking of an InP based resonant tunneling diode relaxation oscillator is demonstrated. The diode is an Al-free InP/InGaP/InGaAs structure. The characteristics of the fundamental oscillating line and its harmonic, including their phase noise are reported.

Reflection and transmission of phase-inversion-waves in oscillators coupled by two kinds of inductors

Abstract: In this study, nonlinear wave phenomena related to reflections and transmissions of the phase-inversion-waves around the discontinuity of the system consisting of two parts of coupled van der Pol oscillators are investigated. Behavior of the phase-inversion-waves around a discontinuity in a coupled system consisting of two kinds of arrays of van der Pol oscillators was classified into 8 types by computer simulations. Further, the mechanisms of the reflection of the phase-inversion-waves at the discontinuity are explained.

Trimmable low voltage oscillator

Abstract: The present invention relates to a trimmable oscillator circuit which comprises a comparator circuit operable to compare an output voltage of the oscillator circuit to a reference voltage and output a control signal in response thereto. The oscillator circuit further comprises an output capacitor, wherein a voltage at a node of the capacitor comprises the output voltage of the oscillator circuit, and the oscillator circuit also comprises a selectively trimmable charge/discharge circuit coupled between the comparator circuit and the output capacitor. The charge/discharge circuit is operable to charge or discharge the output capacitor based on the control signal, wherein a rate of charge or discharge is dictated by one or more user selectable control signals. Thus an oscillation frequency of the oscillator circuit may be trimmed.

Trim effect compensation circuit

Abstract: An oscillator assembly has a voltage controlled crystal oscillator that produces a stable reference frequency. The voltage controlled crystal oscillator is connected to an electronic frequency adjust voltage. A temperature compensation circuit is connected to the voltage controlled crystal oscillator. The temperature compensation circuit provides a temperature compensation voltage to the voltage controlled crystal oscillator. A trim effect compensation circuit is connected between the temperature compensation circuit and the electronic frequency adjust voltage. The trim effect compensation circuit adjusts the temperature compensation voltage in response to a change in the electronic frequency adjust voltage.

Multi-loop relaxation oscillation SQUID magnetometers with large flux-to-voltage transfer functions

Abstract: A multi-loop Relaxation Oscillation SQUID (ROS) with direct voltage readout is fabricated and characterized. We designed and fabricated four-loop ROSs with the size of 5 mm /spl times/5 mm. A maximum voltage modulation of 100 /spl mu/V and a flux-to-voltage transfer function of more than 10 mV//spl Phi//sub 0/ were obtained. With a direct voltage readout flux locked loop (FLL), a magnetic field resolution of 4 to 10 fT//spl radic/Hz was obtained in the frequency range from 0.3 Hz up to the white region. Using this magnetometer, we demonstrated the measurement of a brain response.

Voltage controlled oscillator and communication device using the same

Abstract: A voltage controlled oscillator changes two different frequencies to operate, and includes a resonance circuit, an oscillation circuit, and a buffer circuit. The resonance circuit includes a variable capacity diode, a diode which is a switching element, a strip line resonator, an inductor, a resistor, coupling capacitors, and a DC blocking capacitor. The intermediate tap CT 1, which is located at a position other than the ends in the strip line resonator, of the strip line resonator is grounded via the diode as the switching element, and the DC blocking capacitor. The diode as the switching element is connected to a control terminal via the resistor.

Design of L-band microwave oscillators

Abstract: Oscillators are basic microwave energy sources for all microwave communication systems. Transistor oscillators can be realised using either bipolar or GaAs FET devices. This paper discusses the theory and fabrication of 1.7 GHz negative resistance and feedback type GaAs FET oscillators. A microstrip resonator has been used in the design of the negative resistance oscillator and a feedback type oscillator utilises a lumped element resonator in a feedback network. Simulation for both oscillators has been performed using Agilent ADS software. Both oscillators have been fabricated on an FR 4 PCB. The negative resistance oscillator operating at 1.66 GHz delivers +7.89 dBm output power to the 50 /spl Omega/ load. The feedback type oscillator operating at 1.47 GHz exhibits an output power of +9 dBm. The performance of those oscillators has also been compared in terms of phase noise, showing superior results for the feedback type oscillator.

Giant relaxation oscillations in a very strongly hysteretic superconductive quantum interference device ring-tank circuit system

Abstract: In this article, we show that the radio frequency (rf) dynamical characteristics of a very strongly hysteretic superconducting quantum interference device (SQUID) ring, coupled to a rf tank circuit resonator, display relaxation oscillations. We demonstrate that the overall form of these characteristics, together with the relaxation oscillations, can be modeled accurately by solving the quasiclassical nonlinear equations of motion for the system. We suggest that in these very strongly hysteretic regimes, SQUID ring-resonator systems may find application in logic and memory devices.

Clock extracting device of disc reproducing apparatus

Abstract: A clock extracting device of a disc reproducing apparatus, comprising: an information read-out member for reading information signals from a disklike information recording medium; a voltage control oscillator; a phase comparator for comparing a phase of the information signals read by the information read-out member and a phase of an output of the voltage control oscillator; a frequency comparator for comparing a frequency of the information signals read by the information read-out member and a frequency of the output of the voltage control oscillator; a speed sensor for detecting the frequency of the output of the voltage control oscillator at a reference clock so as to output a speed signal; a gain command unit for designating a loop gain of a clock extracting circuit in accordance with the speed signal outputted from the speed sensor; a charge pump which discharges or draws electric current in accordance with outputs of the phase comparator and the frequency comparator and changes over an output current value in accordance with a gain command of the gain command unit; and a series circuit of a resistor and a capacitor, whose one end is connected to an output of the charge pump and the other end of which is grounded or is connected to a reference voltage; wherein an output voltage between the opposite ends of the series circuit acts as a control voltage for the voltage control oscillator and the gain command unit issues the gain command such that the loop gain of the clock extracting circuit secures a desired operating point in accordance with a read rate of the information signals.

Multimode oscillations in a four fully-interconnected Van Der Pol oscillators

Abstract: This paper investigates a multi-mode oscillations in a four fully-interconnected van der Pol oscillators. In particular, we focus our attention to the asymmetric system where non-resonant double and triple modes, bifurcated from a 3-fold degenerate mode, can exist. As a result, we found that a certain non-resonant double mode cannot be synchronized even if its component frequencies are very close.

Current-feedback magnetic multivibrator with feedback-controlled frequency compensation circuit

Abstract: An improved current-feedback magnetic multivibrator having a constant frequency of oscillation is proposed. Current-feedback magnetic multivibrators are noise-proof, reliable, and highly efficient. However, the frequency of oscillation varies with the load. The proposed multivibrator can compensate the oscillation frequency by feedback control. This circuit succeeds to advantages of self-excited multivibrators.

A novel integrated device - a simulated inductor with voltage control characteristics inversely proportional to the square of control voltage U/sub c/

Abstract: A voltage-variable simulated inductor has been realized as a monolithic integrated circuit with DIP-14 package. It features its inductance with voltage-variable characteristics inversely proportional to the square of control voltage U/sub c/ and can be used as a circuit element to form a linear voltage-controlled sine wave oscillator or filter, especially operating in a low or very-low frequency band. The test waveforms were printed from a PC with a data acquisition board to show the actual properties of the new integrated device.

Bifurcation and chaos in the piecewise-linear forced Duffing-van der Pol oscillator with a diode

Abstract: In this paper, we analyze a forced Duffing-van der Pol oscillator with a diode by the use of a degenerate technique. We consider the case where the diode is assumed to operate as an ideal switch. In this case, the governing equation is represented by a constrained equation. From this equation, the Poincare/spl acute/ map is derived as a one-dimensional map. The generation of various interesting phenomena such as torus and chaos etc. are well explained by the Poincare/spl acute/ map.

On-chip cmos oscillator and current reference therefore

Abstract: Integrated oscillator circuit of the relaxation type, wherein the circuit comprises a controllable current source I(s) and a gate oxide capacitor (Cox) which both have a dependency on a common transconductance s.